Foamed molded bodies configured from foamed synthetic resins such as polyurethane foam are employed in for example seat pads configuring vehicle seats, and in vehicle door interior components. In foamed molded body manufacturing processes, a mold release agent is applied to a cavity inner face of a mold before supplying into the cavity a specific amount of a foamable resin raw material for forming soft polyurethane foam. The mold is then closed, and the foamable resin raw material is foamed and cured. The foamable resin raw material fills the inside of the cavity as it expands, assuming a shape corresponding to the cavity. During this process, defects such as surface hollows and voids can occur in the molded body when air, as well as gases such as carbon dioxide that are generated by the foaming reaction, that are present inside the cavity cannot be adequately discharged to the cavity outside.
Molds are therefore provided with gas discharge holes to discharge gas from inside the cavity. However, providing gas discharge holes on their own can result in foamable resin raw material that has filled the cavity flowing out through the gas discharge holes to the outside of the cavity, resulting in the joint issues of raw material loss, and of necessitating a cleanup operation of the gas discharge holes.
Patent Document 1 (Japanese Patent Application Laid-Open (JP-A) No. 2006-192831) describes disposing inside a mold cavity a gas-permeable member that is configured from a plate shaped gas permeable slab or from nonwoven cloth and to which is attached a gas-impermeable sheet capable of covering a gas discharge hole. In a foam molding process employing this mold, gas inside the cavity passes through the gas-permeable member and passes between the gas-impermeable sheet and a cavity inner face to flow out through the gas discharge hole to the outside of the mold until the foamed resin has filled the inside of the cavity. As the foamed resin fills up the inside of the cavity, the gas-permeable member is pressed against the cavity inner face under the pressure of foaming foamable resin raw material, such that the gas-impermeable sheet blocks off the gas discharge hole. The foamed resin is thereby prevented from entering the gas discharge hole. In Patent Document 1, the gas discharge hole is configured with a uniform internal diameter along its entire axial direction length (namely from an entry side that opens onto the cavity to an exit side that opens onto an outer face of the mold).
In the embodiment illustrated in FIG. 7 to FIG. 10 of Patent Document 1, protruded portions are provided at the cavity inner face at the periphery of the gas discharge hole so as to protrude out toward the cavity inside. During foam molding, when the gas-permeable member is pressed toward the cavity inner face by the foamed resin filling the cavity inside, the gas-permeable member contacts the protruded portions through the gas-impermeable sheet. When this occurs, the gas-permeable member is supported by the protruded portions through the gas-impermeable sheet, achieving a state in which a space that is in communication with the gas discharge hole remains between the gas-impermeable sheet and the cavity inner face, enabling gas inside the cavity to be discharged to the cavity outside through this space and through the gas discharge hole. Then, as foaming and curing of the foamed resin raw material proceeds, the foamed resin presses the gas-permeable member further against the cavity inner face, whereby the protruded portions dig into the gas-permeable member through the gas-impermeable sheet, and the gas-impermeable sheet becomes even closer to the cavity inner face, blocking off the gas discharge hole. The foamed resin is thereby prevented from entering the gas discharge hole.    Patent Document 1: JP-A No. 2006-192831